<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>17.2.1 HTML 事件处理程序</title>
</head>
<body>
    <input type="button" value="Click Me" onclick="console.log('<b>')"/>
    <input type="button" value="showMessage" onclick="showMessage()"/>
    <input type="button" value="showEvent" onclick="console.log(event)">
    <input type="button" value="showValue" onclick="console.log(this.value)">
    <input type="button" value="Clickvalue" onclick="console.log(value)">
    <form method="post"> 
        <input type="text" name="username1" value=""> 
        <input type="text" name="username2" value=""> 
        <input type="button" value="Echo Username" onclick="console.log(username2.value)"> 
    </form>
    <input type="button" value="Clickvalue11111e" onclick="showMessageEvent('hello',event)">

</body>
<script> 
    function showMessage() { 
    console.log("Hello world!"); 
    }
    function showMessageEvent(param1,param2) {
    console.log(param1,param2)
   }
   </script> 

</html>